Comparison of ultrasound-measured age-related, site-specific muscle loss between healthy Japanese and German men

The purpose of this study was to compare the age-related muscle loss in both the appendicular and trunk regions in 207 Japanese and 111 German men aged 20-62 years. Ultrasound-measured muscle thickness (MTH) was taken at eight sites from the anterior and posterior aspects of the body, and the MTH was expressed in terms relative to limb length (MTH/L) or standing height (MTH/Ht). In both the Japanese and Germans, age was correlated with quadriceps MTH (Japanese, r = -0.347; Germans, r = -0.292; both P<0.01) and abdomen MTH (Japanese, r = -0.300, P<0.01; Germans, r = -0.232; P<0.05). On the other hand, hamstring MTH was correlated with age in the Japanese (r = -0.188, P<0.01), but not in the Germans (r = 0.100). There were no significant correlations between age and other limb (i.e. triceps surae MTH/L, Japanese, r = 0.04; Germans, r = 0.05) and trunk sites (subscapula MTH/Ht, Japanese, r = -0.09; Germans, r = -0.02). In conclusion, age-related skeletal muscle loss was strongly observed in the quadriceps and abdominal sites in both the Japanese and German men, although the rate of regular physical activity was different between the two groups.